Femoral head prosthesis



Aug. 10, 1954 M. DOBELLE FEMORAL HEAD PROSTHESIS Filed March 20, 1952 I INVENTORQ Mari/'1? D0 Ze/AP,

0 Z 0 M 552E227 MIE ATTORNEY Patented Aug. 10, 1954 UNITED STATES PATENT OFFICE 2,685,877 FEMORAL HEAD PROSTHESIS Martin Dobelle, Pittsfield, Mass.

Application March 20, 1952, Serial No. 277,658

Claims.

The object of the invention is to provide means for obtaining a functional hip which would otherwise be non-functional when the head of the thigh bone was destroyed, impaired, or injured beyond repair, or where injury or disease has destroyed the hip joint and stifiened the latter so that motion is greatly limited, if not impossible; to provide a femoral head prosthesis which, when in position in the neck of the femur, will be retained in position without danger of loosening except under such conditions as would fracture a strong or healthy bone; and to provide an appliance of the kind indicated which is of simple form and therefore, simple of application with ordinary skill on the part of the surgeon.

With this object in view, the invention consists of a construction and combination of parts of which a preferred embodiment is illustrated in the accompanying drawing wherein:

Figure 1 is a side elevational view of the upper part of a femur in which the head or proximal fragment has been removed and replaced with the improved femoral head, the dotted lines indicating the initial position of the parts in placement. V

Figure 2 is a view similar to Figure 1 but shows the femoral head finally positioned, the dotted lines indicating the relative positions of the parts;

Figure 3 is an axial sectional view of the improved femoral prosthesis, the keys being shown in extended position;

Figure 4 is a sectional view similar to Figure 3 but with the locking keys in retracted position;

Figure 5 is an elevational viewof the key actuator screw;

Figure 6 is an elevational view of the lock screw; and

Figure 7 is an elevational view of one of the locking keys, detached from the device.

In the use of the invention where the head of the femur is pathologically impaired beyond the point where normality can be restored, it is removed and in old injury or disease the socket of the attendant acetabulum is reamed out for the reception of the prosthetic head which is. applied into the neck of the femur to replace the head removed therefrom.

The operation of applying the prosthetic head consists of boring the neck of the femur along its axis beyond a straight line passing through the great and lesser trochanters. The bore having been prepared, there is then applied the prosthetic head H) which is of plastic and stainless steel insert and which is formed with a shank l l, which enters the bore, the lower end of the shank 2 tapering as indicated at I2. The bore, of course, is made with a suitable reamer (or with a drill followed with a ream'er) so that there will be a snug fit between the shank H and the wall of the bore, the latter, of course, being in the medulla.

But the head must be securely anchored to the femur and to this end the shank H is moulded around and has incorporated with it a core it which is formed with a longitudinal bore l l, this bore being of a diameter corresponding to and registering with the bore id in the lower end of the shank H.

The shank H is formed with lateral slots l6 and the core with lateral slots ll and adjacent these slots H, the core carries the lockin keys ls which are pivotally mounted, as indicated at 2%. By reason of this arrangement, the key may be swung downwardly to nested. positions within the periphery of the core it, or they may be swung outwardly to engage the medullary cortex, the former position being shown in Figure 4 and the latter in Figure 3.

But the keys must be actuated to extended position and to this end there is provided a screw it formed with a pilot 2fl-,the latter engaging the heel ends of the keys when the screw is ad'- vanced, the screw threadingly engaging the bore of the core and the pilot moving axially therealong.

A prosthesis is applied, after the preparation of the receiving borein the neck of the femur, by gently driving on the head with a cupped mallet until the shank is fully seated' When this has been accomplished, the screw 59 is advanced and the pilot then engaging the shoulders El on the locking keys, will raise the latter, causing them to penetrate or engage the medullary cortex and thus lock the shank and with it the head in the desired position on the femur.

The screw it is actuated with an ordinary screw driver of which the bit is inserted in the kerf of the head 22 of the screw.

When the locking keys have been fully advanced, the position of the actuating screw lit is retained through the instrumentality of a lock screw 23 threadingly engaged with the upper end of the bore of the post.

It will be noted that the core is terminated just short of the dome of the head, thus forming a shoulder on which the head of the set screw 23 may set, with the head of the screw below the femoral head. Thus there is no projectin metallic part. It will also be noted that the operation of setting the locking keys results in their being raised from a pendant position from their axes to positions normal to the axis of the shank. Thus the slots which they cut in the femur are below them, and the upper hinges have firm; bearings tthroughout their lengths within the neck of the femur, thereby providing a firm anchorage to keep the prosthetic head in place.

With the socket of the attendant acetabulum reamed outwith aistandard cupped; reamer or adequate otherwise, the acetabulumis then in condition to receive the new head with the result that a new hip joint is formed. Because of the inz-- ertness of the material used in the prosthesis, further bony growth, which would defeat its pur pose, is avoided, thus givin an otherwisezcrippledi individual a painless weight-bearing functioning hip.

The invention having been described, what-is claimed as new and useful is:

1. Femoral head. simulating the. natural head of the femur; the samehavin'ga shank insert'able iii a reamedhole formeuin'theneck of the femur, a plurality of" locking members carried in the shank, and shank-encIoSed means for advancing said locking members into engagement with the surrounding bone of the femur.

2. A femoral head' prosthesis comprisinga plastic head simulating thenatural' head of the femur; the same having a shank insertable in areamed; hole formed in the neck of' the femur, the head and shank being formed with an axial" bore, a metallic core encl'o'sed by the shank, locking keys having respectively diametrically o'p-- posed pivotal mountings; and adjusting means for actuating said keys through slots in-theshank the binding engagement with" the medulla-rycortex of the femur; said adjusting means being accessiblethrough the plastic head but unex. posed at any pointof' thesurface-the'reo-f.

3. A femoral head prosthesis comprising a plastic hea d simulating the natural head of the femur, the same having a shank insertable in a reamed hole formed inthe neck of thefemu-r, the headand shank being formed with an ax-ia-t bore, a metallic core enclosed by the shank, locking keys having respectively diametrically opposed pivotal mountings, and normally depending with their free terminals away from the head, an adjusting screw threadinglymou'nted in thebo're ofthe core and having a pilot engageable with the being wholly within thecore so that no portion thereof projects beyond the surface of the head, the screw being actuable through the head.

4, A femoral head prosthesis comprisin a head portion simulating the natural head of the femur, the same having a shank insertable in a reamed hole formed in the neck of the femur, a plurality of locking keys mounted within the shank on respectively oppositely disposed pivotal axes ;.the-keys hanging normally in pendant positi'ons away from? the head} an: adjusting screw threadingly engaged with an axial bore formed in the shank and having a pilot engageable with the heel ends of the keys to elevate them through clearance si'ots in the shank into positions substantiallynormal with the axis of the shank so as to enter and be anchored in the medullary cortex of the femur, the adjusting screw being whollycontained within the shank so that no part projects beyond the surface of the head through which said screw is accessible.

5; A femoral head prosthesis comprisin a head portion simulating the natural of thefemur; the same having a shank irisertable in a reamed"v hole formed inthe neck of the femur, a plurality of lockingkeys mounted within the shank on respective-lyoppositely disposed pivotal: axes, the keys hanging normally in pend'antposiztions away from the head, an adjusting screw: threa'dingly engaged" with anaxial bore formed in the shank and having a pilot'engageable withthe heel ends of" the keys toelevate them through:- cl'e'arance slots in the shank into positions substantially'n'ormal with the axis of the-shank so as to enter and be anchored in the medullary cortex of the'f'emur, the adjusting'screw'bein wholly contained within theshank so that no part projects beyond the surface of the head throughwhich said screw is accessible, the headi having a bore coaxially incident with the axis of the ad justi'n' screw, and a lock-screw: threaded said bore and having: its bearing. on. a shoulder therein, the: lock-screw seated being. below the surf-ace-ofsaid head,

References Cited in the file of this patent UNITED- STATES PATENTS Number Name. Date 2,077,804 Morrison Apr. 20,1937 2,381,950 Hard'inge. Aug. 7,, 1945 2,612,159 Collison Sept. 30,1952

OTHER- REFERENCES La Presse' Medicale; May 3, 1947, page 302. (Gopy in Div. 55.) 

